Thermostatic switch



March 11, 1952 E, J. DILLMAN THERMOSTATIC SWITCH Filed June 22, 1949 FIGJ FIG. 4

JNVENTOR. M. 13% BY MKM M ATTORNEY Patented Mar. 11, 1952 UNITED STATES PATENT OFFICE THERMOSTATIC SWITCH Earnest J. Dillman, Detroit, Mich assignor to Detroit Lubricator Company, Detroit, Mich., a corporation of Michigan Application June 22, 1949, Serial No. 100,709

6 Claims. (01. 200-140) 1 2 This invention relates to new and useful erence, and particularly to Fig. 2, there is shown improvements in thermostatically operated a switch supporting plate or wall I which carries switches and more particularly to a switch structure operated by a thermal expansive power element which has a means for opening the switch in the event of power element failure.

One of the objects of this invention is to provide a new and improved switch structure.

Another object is to provide a switch structure comprising a pair of normally closed switches operated by a single actuating member and operable to be opened upon predetermined movement of the actuating member in one direction or the other.

Another object is to provide a switch structure comprising a pair of normally closed switches actuated by a single actuating member which is operable 'upon predetermined movement of the actuating member in one direction to open one of the'switches and upon a predetermined movement in the opposite direction to open the other of the switches and including means to vary said predetermined switch opening movements.

' Another'object is to provide a novel switch and fluid expansive power element combination.

Another object is to provide a novel switch structure which is operated by a thermal expansive power. element and which includes a means for opening the switch in the event of power element failure.

' Other objects will become apparent from time to time throughout the specification and claims as hereinafter related. r This" invention comprises the new and improved construction and combination of parts and their cooperative relationship to each other which will be described more fully hereinafter and the novelty of which will be particularly pointed out and distinctly claimed.

" In the accompanying drawings to be taken as a part of this specification there is clearly and fully illustrated one preferred embodiment of this invention in which drawing:

Figure 1 is a top plan view of the supporting plate for-the switch structure described herein,

' Fig. 2 is a sectional view taken on the line 22 of Fig; l and showing the switch structure which is the subject of this invention. Fig. 3 is' a sectional view taken on the line 33 of Fig. 2 and shows the novel switch structure'which is the subject of this invention. I

Fig. 4'is a sectional view taken on the line 44 of Fig. 2 and shows an end view of this novel switch construction.

Referring to the drawings by characters of ref 55 member and has secured thereto an open ended casing 2. Secured to the underside of and extending up- Ward through an aperture in the bottom wall 3 of the casing 2 there is supported a power element structure generally designated as 4. The power element structure 4 comprises a cup-shaped casing 5 having an inlet passage 6 in wihch is secured one end of a tube or capillary l, the other end of which has secured thereon a thermal responsive bulb element 8. There is a sleeve member 9 which extends upward through the bottom wall aperture and which is positioned over the open end of the cup-shaped casing 5 and in which there is positioned a reciprocally movable operating rod or thrust member In. Positioned between the inner end of the sleeve member 9 and the open end of the power element casing 5 there is a cupshaped or hat-shaped diaphragm or septum I l which is clamped and sealed at its periphery between the sleeve member 9 and the casing 5. The space enclosed by the diaphragm H and the power element casing 5, and the capillary 1 and bulb element 8 is filled with a thermal expansive material, preferably a volumetrically expansible liquid although a volatile liquid or low melting point solid might conceivably be used. The term fluid or thermally expansi-ble fluid as used in the appended claims is intended as a term generic to and covering a volumetrically expansive liquid, a volatile liquid, or a r-expansible fusible solid. The diaphragm H is operable to transmit fluid expansion to move the thrust rod 10 and also functions to seal the power element casing 5 against leakage. The power element structure 4 just described is more fully described and claimed in my co-pending application, Serial No. 16,541, filed November 23, 1943 for Actuating Mechanism. There is an annular flanged and somewhat cup-shaped spring supporting member [2 having upper and lower flanges and which seats on a shoulder on the end of the thrust rod I0 and which receives one end of a helical spring 13, the other end of which is seated on the annular shoulder of a rockable thrust member Hi. The thrust member M is pivotally carried by a switch operatin lever I5 (which lever carries a contact spring'arm [5 the contacts of which are not shown) and on its other side receives one end of a helical spring 16, the other end of which seats on a flange or shoulder portion of a spring supporting member H. The spring supporting I1 is carried by a screw-threaded adjustment member generally designated as l8 and is operable upon adjustment to vary the compressive force of the spring l6 which in turn determines the compressive force of the spring [3. The lever which is operated through the spring l3, the adjustment mechanism 18, and the other parts shown immediately in cooperation therewith are generally described and claimed in my co-pending application, Serial No. 756,265, filed June 21, 1947, now Patent No. 2,548,887, April 17, 1951 for Snap Acting Device, this structure forming no part of the present invention. There are a pair of posts or supporting, members l9 and which extend downward fromv and are supported by the upper wall I and which carry at their lower ends a supporting bar or member 21 of an insulating material. There are a pair of switch contact arms comprising leaf springs 22. and 23 which are secured to and carried by the supporting member 2| spaced from each other and, having inturned leg portions 24- and 25 respectively which are biased with each other. There is an actuating member: in. the form of a leaf spring. 26 which is secured at one end to. the. supporting member 2| and. which extends between and substantially parallel to the contact springs. 22 and 23 between the overlapping leg portions 24 and25. The actuating spring members 26 has oppositely facing electrical. contact surfaces comprising contacts 21 and 28 which, are engaged by contacts 29 and 30 carried by the contact leg portions 24 and 25 respectively. The actuating spring member 26 has a projecting end portion 3| which engages the flanged member l2 and, which is. operable to he moved thereby for actuation of the. switch arms 22 and. 23. The contact arms, 22' and. 23' make contact through the. contacts 29, 21, 2 8 and: 33 and. comprise a switch structure whichwill be generally designated as 32. The contact arm 22 is connectedto a wire 33 and the, contact arm 23- is connected. to a. wire 34, which. wires" form part of the control circuit external'of this device. The actuating arm 23 is operable upon movement to move. one. of the contact arms. 22" or 23 positively and. tow permit. the other contact arm. to follow it through its. spring biasing force. There is a. stop member 35 which is screw-threadedly and adjustably carried by thewall member I as at 36 and. which has. a flanged lower. end portion 31. which. is operable to engage the contactv arm 22 upon. predetermined downward movement thereof. There is another stop memberv 38 which is screw-threadedly and adjustably carried by" the wall member. I. as at..3.9. and which has a lower tip portion 4.0 whichis engageable with the contact arm 23. upon predetermined upward movement thereof.

In operation this inventioniunctions generaliy' as follows: When the temperature of the power element. bulb 8 is increased the thermal expansive liquid which is enclosed therein will expand and cause the. diaphragm I! to transmit expansive force and movement to the operating rod in. As the operating rod I0 is movedupwardly by the: power element A the lower flange of' the flanged member l2 will engage the end 3| of the actuating spring arm 26 and movethe same up ward; As the spring arm 26 is moved upward the. contact arm 22 is flexed upward. therewith andthe contact arm 23. will follow by reason of itsupward bias until itengages the stop member 381. Further upward movement of the arm 26 after the contact arm 23 has engaged the stop member 38 will cause the arm 23 to break contoward engagement 4 tact between the contacts 28 and 30 and thus open the circuit of which the wires 33 and 34 are a part. In the event that the power element should leak and the thermal expansive liquid escape therefrom the springs I6 and I3 will force the operating rod 10 and flanged member l2 downward. When the flanged member I2 is moved downward in the event of such power element failure its upper flange will engage the end I portion 3| of the spring arm 26 and flex the same downward thus moving the contact arms 22 and 23. therewith. Upon predetermined downward movement of. the spring arm 26 the contact arm 22 which. has followed by its downward biasing force will; engage. the flanged portion 31 of the stop member 35 and will break open the contacts 23 and 21 thus opening the circuit of which the wires 33 and 34 are a part. The stop members 35' and 38' are independently adjustable to determine the amount of movement of the spring arm 26 which isnecessary; to open" the switch structure 32 either onrising temperature or: on power" element failure. It should be noted that the. opening of thecontacts 29 and 2'! which is accomplished in the event of power element. fail ure will also be accomplished in the event that the bulbelement 8 and thermal expansive-fluid therein is" cooled to an extremely low temperature. However, the fluid temperature which would be required for the opening of the contacts" 2'! and 23 would in practice be set solow that it' could never occur normallyand so this feature of construction is in efi'ect limited to safety operation. From the foregoing'it is seen thatthereisprovided'. a simple and inexpensive: switch construe tion which maybe operated bya fluid expansive power element to open a circuit on: rise of temperature. and toclose the circuit on decrease in.

temperature. and; having, a simple and novel means to open the circuit in the event of leakage of fluid. from the. power element.

Having thus described the invention What is claimed and desired to be'securedby Letters- Patent oi the- United States is:-:

L. In an automatically operated-1 switch structure, a power elementincluding an operating, member and athermally expansive fluid for moving said member, said power element being operable upon. thermal expansion ofv s-a-id fluid to move said member in one direction, a spring engaging said member and. urging. the samain. the opposite direction, an actuating member arranged for movement by said operating mom.- ber and having oppositely iacing electrical contactsuriaces, a pair of movable. switch contact arms. each spring biased for contact with the. respective oppositecontact surfacesiof said actu-- ating member andoperable to move with said" actuating memberupon movement thereof,., a first stopmember engageable with one of said contact arms upon predetermined: movement-ofsaidactuating: member in said one direction to stop: further movement of said arm and cause it to. break contact with said actuating. member, a

'secondstop member engageablewiththe other of said contact arms upon predeterminedmovement of said: actuating member in said. opposite direction tostopfurther. movement of. said arm and cause it, to. break contact with. said actuating member, and. said spring being. operable. in..the' event of power element leakage to move said operating member and said actuating member through. said predetermined. movement" in said opposite direction.

2. In an automatically operated switch structure, a power element including an operating member and a thermally expansive fluid for moving said member, said power element being operable upon thermal expansion of said fluid to move said member in one direction, a spring engaging said member and urging the same in the opposite direction, an actuating member arranged for movement by said operating member andrhaving oppositely facing electrical contact surfaces, a pair of movable switch contact arms each spring biased for contact with the respective opposite contact surfaces of said actuating member and operable to move with said actuating member upon movement thereof, a first stop member engageable with one of said contact arms upon predetermined movement of said actuating member in said one direction to stop further movement of said arm and cause it to break contact with said actuating member, a second stop member engageable with the other of said contact arms upon predetermined movement of said actuating member in said opposite direction to stop further movement of said arm and cause it to break contact with said actuating member, said spring being operable in the event of power element leakage to move said operating member and said actuating member through said predetermined movement in said opposite direction, and said stop members being adjustable to vary the respective predetermined movements required for breaking contact with said actuating member.

3. In an automatically operated switch structure for controlling an electric circuit, a pair of switch contact arms arranged for connection in a circuit; said contact arms comprising leaf springs spaced laterally from each other and having laterally inturned contact carrying legs, one overlying the other, and spring biased toward contact; an actuating arm comprising a leaf spring extending between said contact arms and said contact legs and carrying oppositely facing contacts engaged by said contact legs for electrical conduction therebetween; means for opening and closing the circuit controlled by said switch structure comprising a power element having a reciprocal operating member and a thermal expansive fluid for moving said member, said operating member being movable in one direction by thermal expansion of said fluid, a spring engaging said operating member and urging the same in the opposite direction, said operating member engaging said actuating arm for movement thereof, said actuating arm being operable upon movement in said one direction to move one of said contact arms positively therewith and the other contact arm following by its biasing force, a first stop member engageable with said other contact arm after predetermined movement with said actuating arm to stop further movement of said contact arm and permit said actuating arm to move away from it and open the circuit controlled thereby; and means to open the circuit controlled by said switch structure in the event of leakage of fluid from said power element and comprising a second stop member engageable with said one contact arm upon predetermined movement with said actuating arm in said opposite direction to stop further movement thereof and break contact with said actuating arm.

4. In an automatically operated switch structure for controlling an electrical circuit, a pair of switch contact arms arranged for connection in a circuit; said contact arms comprising leaf springs spaced laterally from each other and having laterally inturned contact carrying legs, one overlying the other, and spring biased toward contact; an actuating arm comprising a leaf spring extending between said contact arms and said contact legs and carrying oppositely facing contacts engaged by said contact legs for electrical conduction therebetween; means for open ing and closing the circuit controlled by said switch structure comprising a power element having a reciprocal operating member and a thermal expansive fluid for moving said member, said operating member being movable in one direction by thermal expansion of said fluid, a spring engaging said operating member and urging the same in the opposite direction, said operating member engaging said actuating arm for movement thereof, said actuating arm being operable upon movement in said one direction to move one of said contact arms positively therewith and the other contact arm following by its biasing force, a first stop member engageable with said other contact arm after predetermined movement with said actuating arm to stop further movement of said contact arm and permit said actuating arm to move away from it and open the circuit controlled thereby; means to open the circuit controlled by said switch structure in the event of leakage of fluid from said power element and comprising a second stop member engageable with said one contact arm upon predetermined movement with said actuating arm in said opposite direction to stop further movement thereof and break contact with said actuating arm, and said step members each being adjustable for varying the respective predetermined movements required of said actuating arm.

5. In an automatically operated switch structure, a power element including an operating member and a thermally expansive fluid, said operating member having a predetermined normal range of movement, said fluid being operable in response to increased temperature to move said operating member in one direction, a spring engagin said operating member and urging the same in the opposite direction, a switch having normally closed contacts comprising two contact carrying arms biased for contact engagement, one of said arms engaging said operating member for movement thereby, the other of said contact arms maintaining engagement with said one arm throughout said ran e of movement, said spring being operable in the event of leaka e of fluid from said power element to move said operating member in said opposite direction beyond said range of movement, and a stop member positioned outside said range of movement in said opposite direction and en ageable with said other contact arm to step further movement of the same in said opposite direction thereby to open said closed contacts.

6. In an automatically operated switch structure, a thermal element including an operating member and a. thermally responsive member, said operating member having a predetermined normal range of movement, said responsive member being operable in response to change temperature to move said operating member in one direction, a spring engaging said operating member .and

v urging the same in the opposite direction, a switch having normally closed contacts comprising two contact carrying arms biased for contact engagement, one of said arms engaging said operating member for movement thereby, the other of said 7 contact. arms maintaining engagement with said onearmithroughout said-range of movement, said spring; and" said responsive member being openable" in the event of abnormal movement of said responsive member in said opposite direction to move said operating member in said opposite direction beyond: said range of movement, and a stop member positioned outside said range of movement in said opposite: direction and engageablewith said other contact arm to stop further movement of the same in said opposite direction thereby to open said closed contacts.

EARNEST. J; DILLMAN;

REFERENCE S CITED The following: references are of record in: the

Number Name Date 1,916,669 Kuhn et a1 July 4 ,1933 1,957,517 Williams May 8, 1934 2,002,467 Blodgett .May 21,1935 2,080,586 Varley May 18, 1937 2,456,112 Dodd -Dec. 14, 1948 2,460,762 Minnich- Feb. 1, 1949 

